'02 Impala LS problems/questions

My '02 Impala LS has started running rough every so often (twice now) right after startup. It feels like a miss. The check engine message doesn't come
up.
I also noticed a grainy deposit inside my oil cap, kind of like oily sand. But, the "grains" are softer and if you rub them between your fingers they smooth out into kind of a paste. The color is dark brown/black.
I have been keeping an eye on my coolant level (wary of the leaking manifold gasket problem) and it looks ok. The last oil change was a month or so ago with whatever stuff the local dealership uses. Any ideas out there? Thanks.
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The deposit under the oil cap seems to indicate the possibility of a leaking manifold gasket problem.
Ian has pictures on his site that show it.
If your oil filler cap looks like this:
http://members.shaw.ca/ianrmac/Images/DSC00660-1.JPG
get to your dealer ASAP.
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It doesn't look like that (no yellowish gunk), and I don't see any evidence of coolant on the dipstick. I noticed this deposit just recently, and it is coincidental with a dealer oil change a couple months ago (I usually do oil myself and use Mobil1, but they changed it for me without my asking them to the last time I had it in).
I've never noticed any kind of deposits on any of my vehicles when using Mobil 1, so I might just change it again ahead of time and see if it goes away.
Thanks for the tip, though - the whole reason I even look at the cap periodically is to check for the "gunk of death".
wrote:

right
come
sand.
they
manifold
ago
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probably just a partially clogged injector. A very common problem with this car. Have then flushed (free because it falls under the emissions warranty)

right
come
manifold
ago
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Injector problems won't cause crankcase deposits.
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I would certainly take a sample of engine oil and send it in for analysis to make sure that the dreaded intake manifold leak isn't happening.
http://www.blackstone-labs.com /
They will send you the sampling kits for free.
Cost for the oil analysis is $20 for the basic analysis, or $35 for analysis plus expert interpretation by Terry Dyson.
It is well worth it to check up on these engines.
John
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